Staging fuel nozzle

Abstract

A main swirler of a triple annular configuration that is partitioned by a pre-filmer and a separator is installed in an inlet port of a main air flow channel. The vicinity of the inner wall of the main air flow channel provided with a main fuel injection port is bulged radially outward from the innermost surface (innermost surface of a small swirler) of a main swirler. Further, a distance from the main fuel injection port and the pre-filmer is set such that an effective opening area between the pre-filmer and “the inner wall of the main air flow channel provided with the main fuel injection port” is equal to an effective opening area of the small swirler. The swirling directions of the swirlers of the main swirler are “clockwise”-“counter-clockwise”-“clockwise” respectively along the radial outward direction when the swirling direction of the innermost swirler is taken as “clockwise”.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a staging fuel nozzle of a gas turbine engine, and more particularly to a staging fuel nozzle that further increases combustion efficiency in a low or medium load mode of the engine and contributes to further reduction in NOx in a medium or high load mode of the engine.[0003]2. Description of Related Art[0004]A rich-lean combustion system based on diffusion combustion has been used in combustors of conventional jet engines for aircrafts. With such a combustion system, the correlation between the equivalent ratio φ and NOx generation amount has an almost symmetrical convex curved distribution with a center close to φ=1. Therefore, by conducting combustion in a rich state (fuel-rich state) with φ>1 in the upstream portion inside the combustor and then introducing air, it is possible to include combustion in a lean state (fuel-lean state) with φ<1 and avoid the combustion in the vicin...

AI Technical Summary

Benefits of technology

[0029]In order to reduce the amount of NOx generated from the main flame, it is important to atomize the fuel and mix the fuel homogeneously with air. In a fuel nozzle of a pre-filming type, fuel jet collides with a cylinder (liquid film forming body) and forms a fuel film on the inner surface of the cylinder, and the fuel atomization is conducted by the inner and outer air flows at the downstream end of the cylinder. In such a fuel nozzle, in order to attain a high degree of atomization, it is necessary that the fuel jet is caused to reach the cylinder reliably even when the amount of fuel is small and the air flow has a high speed at the downstream end of the cylinder. In accordance with the present invention, the inner wall surface of the main air flow channel where the fuel injection port is provided bulges radially outward from the innermost sluice of the swirler located on the upstream side. Therefore, the fuel jet can reliably reach the cylinder and the air flow speed can be increas

Problems solved by technology

However, since the amount of air for improving the atomization of fuel is less than the total amount of air passing through the main air flow channel, the effect thereof is small.

As described hereinabove, in all of the above-described staging fuel nozzles, fuel is premixed with a sufficient amount of

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